Just bought a 1997 PRE 2150wt. Engine has 264 hours, I've put about 6 on it.

Yesterday, we were out wakesurfing (6 adults and 3 kids in the boat) when the tranny started to slip. At first we thought it was cavitation, so we kind of ignored it. Then when we started to wakeboard it was still there and, because we were giving it more power it was much more noticable. Basically here's what it does: It idles fwd and back smooth and clean. When you apply throttle, like to get a boarder up, it grabs for a second, then the engine revs for about a 1/2 sec and then catches again. Once it grabs it seems to be ok, or at least if its slipping its hard to feel. If you accelerate slowly, it is fine.

My first thought was that the tranny fluid was low, so I got the boat back into my driveway and about as level as I can, then checked the fluid level. With the engine cold (sat overnight) the fluid level comes right up to the full (cold) mark on the dipstick. The fluid also looks very clean and there appears to be no sign of water in there. Previous owner says it was changed over the winter.

The tranny is a Velvet Drive 1:1 model#10-17-004 and the motor is a mercruiser GM 350 EFI. Outside of the tranny and the rest of the motor is very clean, no sign of leaks at all.

Anyone got any ideas what's going on and what I can do to test/fix it??

when was the last time it was changed -- try adding a psi gauge in line and keep an eye on it. also make sure trans is going into full detent, forward and rearward. (possible a brkt has came loose and allowed the adjustment of the cable to move slightly. i had trouble w/ this w/ an older boat i had and it was a bear to find the problem.. but do not over look it --than can get expensive...

My 93 echelon did the same thing last season. it started to just slip a very small amount so i just checked the oil and it was fine. i thought maybe it was cavitation as well. well then it gradually got worse and worse. eventually it completely gave out all the way on the other side of the lake. all it would do was just idle while it was in gear. if i gave it any throttle it would slip. had to "troll" for about 25 min to get back to the dock. it was very wierd how it went from "kind of slipping" to "absolutely nothing" pretty much instantly. i ended up tearing it down and replacing all of the plates and seals. it is also a velvet drive

I have that tranny in my '86 and it did the exact same thing to me about a 2 months ago. I changed the oil, drained the lines and cooler, and made sure the screen inside the drain plug was clean and the problem has not returned. Your tranny oil dosn't look red enough to me, make sure you use automatic trans fluid. Fill to the full line, start and idle in gear for a short time to fill lines, cooler, ect. Shut off and immediately add oil back to full line. Good luck hopefully you haven't ruined clutch plates.

Sounds exactly like what my buddies was doing. He just sent it off to be rebuilt for $750 from this guy:

These transmissions can be purchased for asking price or higher and you must have a good rebuildable transmission for exchange, They are: Borg Warner Velvet Drive 10-17-001 thru 10-17-004 also 10-04 and 10-05 v-drives, and may be known as a powerslot transmission, they are found in many different ski and pleasure boats such as a Mastercraft, Correct Craft, Malibu, Sea Ray and many more. We are the countries largest overhauler of these transmissions, We also handle PCM 40 and 40a's 1:1 and 1.23:1, We service p300 and p400 series inline and v-drive Paragons and ZF Hurth 450a and 630a and 630v. we also stock rebuild exchanges on our shelves. for any questions please send to www.fantasticfinishmarine .com

We service all types of marine transmissions for pleasure, work or ski boats. our transmissions come with a one year unlimited hour warranty and are dynamically spin tested to assure proper operation when installed. You can call us toll free at 877-369-6693 for questions you may have. we are a family owned business and have over 35 years combined experience in marine transmissions and can offer many references of satisfied customers